DETERMINATION OF SEDIMENT TRANSPORT PATHS ON A MACROTIDAL SHOREFACE: COMPARISON OF THE “GAO AND COLLINS” METHOD WITH NEAR-BED CURRENT MEASUREMENTS

摘要

The applicability of grain-size trend analysis for determining sediment transport pathways was investigated on a macrotidal shoreface of the southern North Sea, following the Gao and Collins (1992) method. The sediment transport pattern inferred from the grain-size trend analysis shows a good correspondence with tidally-driven near-bottom currents measured in the vicinity of the sediment sampling sites, which were setting alongshore. Comparison of threshold shear velocity for sediment motion with estimates of bed shear velocity obtained from near-bottom current data recorded simultaneously with sediment sampling indicates that sediment transport was certainly occurring when sediment samples were collected, suggesting that the grain-size trends observed in the surface sediments probably reflect the last transport event. Our results show that grain-size trend analysis can be very efficient for determining the transport pattern of the last sediment transport event when sampling is limited to the thickness of the active layer of sediment remobilization.